In summary, based on BMM the variable blocks \(\mathbf {W}\)  and \(\lbrace \Theta _{l}\rbrace \) 
will be updated cyclically in closed-forms until some convergence
criterion is met. The SQUAREM [1]} is used as
an off-the-shelf accelerator to solve the nonlinear fixed-point update.
The overall algorithm is summarized in Algorithm REF 
with the convergence properties established in Theorem REF .
